Re: [dmarc-ietf] ARC, DMARCbis WGLC - Issue 144 Mention of ARC in DMARCbis

[John Levine <[e-mail]>]

It appears that Murray S. Kucherawy  <[e-mail]> said:
>Can you give an example, even if only a hypothetical one?

I'm not Emmanuel but people at large mail systems have told me that
the biggest value of ARC is to deal with mailing lists that do lousy
spam filtering. Lists often let anything through that has the address
of a subscriber on the From: line. Mail systems see legit lists that
gush spam when some bot starts sending mail to the list with fake
subscriber addresses, because the bot herder is using address pairs
from stolen address books.

While we all know the reasons that you don't want to enforce DMARC on
the mail coming out of a mailing list, it makes a lot more sense to
enforce it on mail going into a list. You can use ARC to look back and
see if the mail was aligned on the way in and if not treat it as spam.

R"s,
JOhn